Safety control for gaseous fuel burners



L A T E m K S E G S SAFETY CONTROL FOR GASEOUS FUEL BURNER-S Filed Sept. 24, 1941 2 Sheets-Sheet l INVENTORS LSAMUEI g EsKnv y CHARLES KASTROBEL.

ATTRNEY.

Au. 14, 1945. I SVG. EsKlN ET AL 2,332,215

SAFETY CONTROL FOR GASEOUS FUEL BURNERS Filed Sept. 24, 1941 2 Sheets-Sheet 2 INVENTORS LSAMUELN E6KIN.

/7 BY Crmmzs K. \STROBEL.

ATTORWALEK Patented Aug. 14, 1945 SAFETY CONTROL FOB GASEOUS FUEL BUBNERS smut! c. Eskln and crimes 1:. smut-1, Pittsburgh, Pa. assignors to Robertsha w Thermos stat Company, Youngwood, Pa., a corporation of Pennsylvania Application September 24, 1941, Serial No. 412,150

9 Claims.

This invention relates. to safety controls for gaseous fuel burners and, more particularly, to electrically operated controls therefor.

Gaseous fuel burners such as domestic gas ranges may have a main burner, a pilot burner ignited by an electric igniter, and means for preventing the flow of fuel to the main burner should the pilot fail to light or be extinguished after a previous lighting. It is desirable in most cases to ensure instant fighting of the pilot burn- 10 b er after the fuel Supply thereto begins. This is particularly the casein view of the growing use of liquefied petroleum gases, such as butane and propane, in domestic gas ranges. The prolonged escape of such unburned fuel is seriously detriis mental to the health of users. While a complete shut-off feature may be incorporated in such systems and is a desirable safety measure, it is apparent that serious consequences might follow upon failure of the pilot gas to ignite and bring the safety into operation. It is, therefore, an object of this invention to ensure immediate ignition of the pilot burner after the fuel supply is first turned on.

Another object of the invention is to prevent flow of fuel to the main burner whenever the pilot fails to ht.

Another object of the invention is to shut off the supply of fuel to both the main and pilot burners upon physical failure of the ignition means or upon failure ofthe electric current supply.

Other objects and advantages will become ap parent from the following description taken in connection with the accompanying drawings, 86

wherein:

Fig. 1 is a schematic view of a control system for a gaseous fuel burner embodying this invention,

Fig. 2 is a similar schematic view of a modifled form of control, and

Fig. 3 is a similar view of a further modification. a

Referring more particularly to Fig. i of the drawings, a. gaseous fuel burner I0 is supplied with fuel by a main fuel pipe l2. Such fuel supply is controlled by a main valve II which may be either manually or thermostatically operated. Interposed in the fuel supp y pipe l2 between the main valve II and burner I0 is a solenoid gas valve Ii of any known type which may be arranged, as in this instance, to be opened by energization of the solenoid and closed by gravity.

Apilot burner I8 is associated with the main fuel burner it and receives fuel from the fuel Electric current for the operation of the sole- V noid valves I6 and 22 is supplied by the line wires :24 connected to the primary of a transformer 25. The secondary of the transformer 25 is connected by a wire 26 to one-terminal of a main switch which, in this instance, is incorporated in the main valve it. Any suitable means may be used to close the switch when the main valve 14 is rotated to open position. The other terminal of the main switch is connected by a. wire 28 to one terminal of the solenoid valve 22 for the pilot burner l8, the other terminal of the solenoid valve 22 being connected by a wire 30 with one end of a resistor member 32 positioned in the path of the flame from the pilot burner I 8.

The resistor member 32 may be in the form of a coil of wire formed from material having normally a. relatively low resistance and a positive temperature coeflicient of resistance. Such elements are known as ballast resistors, but it will be apparent that other types of flame sensitive devices or thermal resistance elements having the required characteristics may be substituted. In utilizing a. ballast resistor for the purpose of this invention it is necessary that the gas valve 22 in the absence of a flame from the pilot burner It. The selection of a suitable coil is therefore dependent upon the voltage to be.

used in the system as will be apparent to those skilled in the art.

The end of the ballast resistor 32 opposite that connected to wire 80, is connected by a wire 36 with one end of an electric wire incandescent igniter' 36, the other end of which is-connected by a wire 38 to the secondary of the transformer 25. In this embodiment an adjusting resistance element Ill is interposed in the circuit between the igniter 38 and the transformer 25 to limit the current supply to the igniter 36.

The solenoid gas valve It for the main fuel burner H) is connected in series circuit with the pilot burner solenoid valve 22 and the igniter 86 and in parallel circuit with the ballast resistor 32. Such connection is made by a wire 42 which connects the wire 30 with one terminal of the solenoid gas valve 16, while the other terminal thereof is connected by a wire it to 44 and is connected at one end to the wire 24 and at the other end to one terminal of a mercury switch", the other terminal of which is connected by a wire 52 to the wire 28.

The mercury switch 58 is preferably of the type having a specified time delay period upon opening and an instantaneous closing. Switches of this type are disclosed n Patents Nos. 1,778,- 439 and 2,224,873 among others, towhich reference may be had for a fuller description.

The mercury switch 58 is normally closed and is adapted to be operated to open position after a time delay period by an electromagnetic actucury switch 50 is connected as described across the secondary of the transformer 25 through the main switch incorporatedinthe valve I4.

In the operation of the safety control apparatus shown in Fig. 1 the closing of the main switch of valve I4 is effected upon opening of this valve as described and permits fuel to flow in the main fuel pipe I2 and the conduit 28 as far as the main burner solenoid valve I6 and the pilot burner solenoid valve 22, respectively. The electric current flows through the wire 26 from the secondary of the transformer 25 through the main switch of valve I4 and through the wires 28 and 52 to the mercury switch 58. This switch being closed at this time, the current flows therefrom through the wire 46 and wire 34 to the ignition coil 36. The wire 38 which is connected to surround it have had time to fiow away. The

opening of the mercury switch causes current to flow through the wire 28 to the pilot burner solenoid valve 22 and then by way of wire 38 and wire 42 to the main burner solenoid valve I6. The

wire 44 which is connected to the other terminal of the main burner solenoid valve I6 conveys the current to wire 46 which is'connected to the wire 34 of the ignition coil circuit. At the same time the ballast resistor 32 which isshunted across the main burner solenoid valve I6 is also 4 introduced into the circuit.

Energization of the pilot burner solenoid valve 22 by the means described causes it to open and permit fuel to flow through the conduit 28 to the pilot burner I8 where it is ignited by the ignition coil 36. The flame of the pilot burner heats the ballast coil 32 and its temperature increases with corresponding increase in its resistance until suflicient electric current is .caused to flow through the main burner solenoid valve-I6 to open this valve. Consequently, the fuel then I 2,382,216 a. wire 46. I The latter wire 46 carries a cut-out to'the main burner I8 becomes lighted by'the flame from the pilot burner I8 and the ignition sequence is completed.

From the sequence of operations described it will be apparent that the pilot burner fuel supply is not permitted to flow thereto until a definite period after the ignition coil has been enersized. The flow of fuel to the main burner is not permitted until after the pilot flame is burning and the ballast coil becomes heated thereby. It

will furthermore be apparent that if the ignition coil burns out or becomes open circuited the gas supplies to both the main and pilot burners are shut off. If the ballast coil becomes open circuited the cut-out in series with the main burner solenoid valve causes this valve to close.

It is of importance that the turning on. then off and then on again of the main switch does not cause escape ofunburned fuel due to opening of the main burner solenoid valve before the ignition coil has reached igniting temperature as may occur in other forms of control. The main burner solenoid valve of this invention remains closed until the time delay period has expired regardless of the speed of recycling the control. The instantaneous reset feature of the circuit for on-off-on cycles is thus of great advantage.

The embodiment of the invention shown in Fig.

I 2 of the drawings has the described features with provision for preventing current flow through the main burner solenoid in the event that the pilot burner solenoid becomes short circuited. In this embodiment a main fuel burner 68 is supplied with fuel by a main fuel pipe 62 controlled by a'main valve 64 and having a main burner solenoid gas valve 66 interposed therein. A pilot burner 68 is associated with the main fuel burner 68. and receives fuel from the fuel supply pipe 62 by way of a conduit I0 connected thereto between the valve 64 and the main burner solenoid gas valve 66. In this embodiment the pilot burner solenoid gas valve I2 which is interposed in the pilot burner conduit I8 is of a special type having a front contact I4 which is-adapted to be operated between open and closed positions by normal movement of the solenoid armature included in such types of valve.

Electric current for the operation of the valves 66 and 12 is supplied by the line wires I6 connected to the primary of a transformer I8. The secondary of the transformer I8 is connected by a wire 88 to one terminal of a main switch which, as in the previous instance, is incorporated in the main valve 64. Any suitable means known to those skilled in the art may be used to close the switch when the main valve 64 is rotated to open position. The other terminal of the main switch is connected by wires 62 and I88 to one terminal of the solenoid valve 12 for the pilot burner 68, the other terminal of the solenoid valve 12 being connected by wires 84 and H2 with one end of the ignition coil 86. The other end of the ignition coil 86 is connected by a wire 88 to the secondary of the transformer I8, there being an adjusting resistance element 98 interposed in the circuit between the igniter 86 and the transformer I8 to limit the current supply to the i niter 86.

In this embodiment the main burner solenoid valve 66 is in parallel circuit with the igniter 86 and the pilot solenoid valve I2. Such connection is made by a wire 92 extending from the wire 82 to one terminal of the front contact I4 Permitted to flow throu the mam fuel p p I! 76 of the solenoid valve I2. The .other terminal of the front contact 14 is connected by a wire 84 to one end of a ballast resistor 86 similar to that described in connection with the rrevious last resistor 86 is thus in parallel circuit with the main burner solenoid valve 68.

I The mercury switch I64 of this embodiment has one terminal connected by a wire I66 to the wire 82 at the junction'of the wire I68 therewith. The switch I64 is thus connected to one terminal of the solenoid valve 12. The other terminal of the mercury switch I64 is connected by a wire I I6 to the wire 84 at the junction of the wire I I2 therewith. The connection of the 4 switch I64 to'the' other terminal of the pilot burner solenoid valve I2 is thus completed. The electromagnetic actuator 4 for the mercury switch I64 has one terminal connected by a wire H8 to the wire 82 at the junction of the wire 82 therewith, while the other terminal thereof is connected by a wire II8 to the wire 88.

Connected in series circuit with the parallel mesh of the main burner solenoid valve 66 and ballast resistor 86 is a series resistor I26 having a wire I22 connecting one end thereof with the wire 98 and awire I24 connecting the opposite end thereof with the wire 88 at the junction of the wire II8 therewith.

The operation of the device shown in the embodiment of Fig. 2 is commenced by closing of the main switch ofvalve 64 which opens the valve and permits fuel to flow in the main fuel pipe 62 and the conduit 16 as far as the main burner solenoid valve 66 and the pilot burner solenoid valve I2, respectively. The electric current flows through the wire 86 from the secondary of the transformer 18 through the main switch of valve-64 and through the wires 82 and I66 to the mercury switch I 64. This switch being closed at this time, the current flows therefrom through the wire H6 and wire 84 to the ignition coil 88. The wire 88 which is connected to the other end of the ignition-coil 86 conveys current through the adjusting resistor 96 back to the secondary of the transformer 18. The current at'this time also flows through the wires H6 and H8 to the electromagnetic actuator II4 of the mercury switch.

After a. definite time delay, which in this instance may be eighteen seconds, the mercury switch I 64 opens. tion coil has reached igniting temperature and the unburned gases which ordinarily surround it have had time to flow away. The opening of the mercury switch causes current to flow through the wlre'i66 to the pilot burner solenoid valve 12 and then by way of wire II2 through the ignition coil circuit. The pilot'burner solenoid valve I2 being thus energized, it is moved to open position and the flow of fuel from the pilot burner 68 is ignited by the igniter 86.

During this period the igni- When the pilot solenoid valvel2 opens, the

front contact I4 thereof is automatically closed by movement of the solenoid armature. 'Such closing of the front contact 14 causes current to flow by way of the wires 94 and I62 to the main burner solenoid valve 66. However, at this time sufficient current does not flow through the main burner solenoid valve 66 to move it to open position. When the pilot flame-heats the the transformer I46 to 3 ballast resistor 84 suIllciently its resistance; in-

creases and ftoi 'iiow through the solenoid ofthe burnerfsolenoid $8.8 valve 55 600M116 indllierflflb reel to flow to the main j flowing' from the main burner 66 is bythe flame from the pilot burner 68".

As will be alibarentrtbe'jem oaimelit own in Fig. 2 has all the desirable features of the embodiment shownin Fig. 1. Moreover, in the embodiment shown in 2 short circuitingjoi the pilot solenoid will cause the front contact 14 thereon to remain o en so" thntfno current can flow through the solenoid valve 66 to cause operation thereof. M An alternate formof the modification shown in Fig. 2, but substituting a fdoubletiinedelay mercury switch for thej front of pilot solenoid valve, is shown Big. 3. "In this enibodiment a main fuel burner, I36 is supplied with fuel by a main fuel pipe iilcontrolled by a main valve I34 and having a mainburner solenoid gas valve I36 therein. A pilot burner m is associated with the ma n fuel burner I 36 and receives fuel from the fuel supply pipe I82 by way of a conduit I48 connected thereto between the main valve'lfl and the main burner solenoid gas valved; embodiment the pilot burner solenoid gaswal've 1'42 which is interposed in piIotQburner conduit tion with the embodimentof, a Electriccurrent for, the operation or the lsolenoid valves I66 and I42 is supplied bythefline wires in connected to the mii arybr tmosformer I46. The secondaryoffthetransformer I46 is connected by a I48 tonne terminal I46 may be similar tothat incommeof a main switch which,asin theiprevious instances, is incorporated inthe 'main valve I34 and 40 the art may be used to close the switchfwhen any suitable means known'byf those skilled fin the main valve I34 is rotated to open position. The other terminal of the main switch is connected by wires I56 and, I52, to one terminal of the solenoid valve I42 for the pilot burner I38, the other terminalof the solenoid valve I42 being connected by wires I54 andl56 with one end of the ignition coil lil. The other end of the ignition coil I58 is connected by a wire, I66'to the secondary of the transformerI, there being an adjustingresistance element I62, interposed in the circuit between the 'igniter I58. and limit'the current Supply totheigniter I68. I

As in the embodiment or Fig. 2 the main burner solenoid valve I36 is connected in a second circuit which is in parallel circuit with that of the pilot solenoid valve I42. However, alsoas in themevious embodiment, a ballastcoil I64 forms part of the main burner solenoid circuit and is ,connected in parallel circuit withthe main burner solenoid valve I36. The connectionsof the ballast coil I64 to the main burner solenoid valve I36 are made by the wires I66and I68, there being a cut-out I16inoorporatedin the wire I66 between the main burner solenoid valve I36 and the ballast coil I64; Connected in series circuit with the parallel mesh of the burner solenoid valve I36 and'the ballast resistor ,I 64,;is a series resistor I12 having a I14 connecting one end thereof with the wire, I 66 'and, a wire I I6 connecting the opposite end thereof withthe wirel66. f j

The double-time delay mercury 'switch previously mentioned may comprise a pilot solenoid .valve switch "8V and a main burner solenoid valve switch I88. Both switches are normally closed and may be actuatedto-open position by a single solenoid I82 having one terminal connected by a wire I88 with the wire I88 and the other terminal connected by a'wire I88 with the wire I88. The mercury switch I18 for the pilot burner solenoid valve I 82 is connected in shunt therewith by the wires I88 and I88, the wire, I88 being connected to the wire I88 and the wire I88 being connected to the wire I88. The mercury switch I88-for' the main burner solenoid valve I88 isconnected in shunt with the parallel mesh of this valve I88. the ballast coil I88 and the cut-out I18.

Such connection is made by a wire I82 connecting one terminal of the switch I88 with the wire I88 and by a wire I88 connecting the other terminal of the switch I88 with the wire I88 between the cut-out I18 and ballast coil I88. The circuit.

of the series resistor I12 in series with the parallel mesh of ballast coil I88 and main burner solenoid valve I38 is completed by a wire I88 connected at one end to the wire I82 and at the other end to igniter 158. After a further delay period, the

mercury switch I88 opens and causes current to flow 'to the main burner solenoid valve I88.

' Meanwhile, the pilotv flame has heated the ballast resistor I88 during the delay period to increase its resistance and permit sufllcient' current to flow through the main burner solenoid to energize it and open the valve. The fuel then flows from the main burner I38 to become ignited by the pilot burner flame and the cycle is complete.

We claim: 1 1. In an electrical ignition system for fuel burners having main and pilot burners and 'means for supplying fuel thereto, an electric igniter for the pilot burner, separate electrically operable means energizable for actuation to a position for admitting fuel to the main and pilot burners when current of sufllcient value is supplied to said fuel admitting means, an energizing circuit including said igniter and fuel admitting means, control means electrically connected to said fuel admitting means for preventing the same from receiving current of said value for a predetermined period following energization of said igniter, said control means including an initially closed switch which opens-after a timedelay period following energization of said control means and resets for such delay period substantiallyinstantaneously upon deenergization of said control means, and a thermal resistance element electrically connected to said main burner fuel admitting means and located to be heated by a flame at the pilot burner, said element being adapted to prevent said main burner fuel admitting means from receiving current of said value for actuation thereof until said element is' heated by said flame.

2. In an electrical ignition system for fuel burners having main and pilot burners and means for supplying fuel thereto, an electric igniter for the pilot burner, separate electrically operable means. energizable for actuation to a position for admitting fuel to themain and pilot burners when current of suflicient value is supplied to said fuel admitting means, an energizing circuit including said igniter and fuel admitting m'eans. control means for preventing said pilot burner fuel admitting means from receiving current of said value for a predetermined period following energization of said igniter, said control means including an initially closed switch in shunt with said pilot burner fuel admitting means and being adapted to open after a time-delay period following energization of said control. P means and to reset. for such delay period substantially instantaneously upon deenergization of said control means, and a thermal resistance element in shunt with said main burner fuel admitting means and located to be heated by a flame at the pilot burner, said element having'insuflicient resistance value until heated by said flame for current of said suflicient value to be supplied to said main burner fuel admitting means.

3. A safety control apparatus for gaseous fuel burners having main and pilot burners and means for controlling the supply of fuel thereto,

said apparatus comprising an electric igniter for said pilot burner energized by operation of said controlling means, a normally closed solenoid valve in series circuit with said igniter for preventing the supply of fuel from passing to the pilot burner from said controlling means, and a control relay for shunting said valve, said relay comprising a mercury switch occupying a closed position when said circuit is deenergized and having time-delayed movement to open position permitting theigniter to reach igniting temperature before the solenoid valve opens.

.4. A safety control apparatus for'gaseous fuel burners having .main and pilot burners and means for controlling the supply of fuel thereto,

said apparatus comprising an electric igniter for said pilot burner energized by operation of said controlling means, a normally closed solenoid valve in series circuit with said igniter and intercepting the fuel supply to the pilot burner, a control relay having a timing element connected in parallel circuit with said solenoid valve and operable to delay. actuation thereof to open position until the igniter reaches igniting temperature, a

normally closed solenoid valve electrically connected with said igniter and pilot burner solenoid valve for preventing the supply of fuel from passing to the main burner from said controlling means. and a thermal resistance element electrically connected tothe main burner solenoid valve and exposed to a flame upon operation of the .pilot burner for governing the operation of said last named valve.

5. A safety control apparatus for gaseous fuel burners having main and pilot burners and means for controlling the supplyof fuel thereto, said apparatus comprising an electric igniter for said pilot. burner energized by operation of said controlling means, a normally closed solenoid valve in series circuit with said igniter and intercepting the fuel supply to the pilot burner, a control relay having a timing element connected in parallel circuit with said solenoid valve and operable to delay actuation thereof to open position until the igniter reaches igniting temperature, a normally closed solenoid valve electrically connected with said igniter and pilot burner solenoid valve for preventing the supply of fuel from passing to the main burner from said controlling means. and a thermal resistance element having normally a relatively low resis ance and a positive temperature coeiiicient of resistance electrically connected in parallel circuit with said main burner solenoid valve and exposed to the flame of the pilot burner for governing the operation of said last named valve.

6. A safety control apparatus for gaseous fuel I burners having main and pilot burners and means for controlling the supply of fuel thereto, said apparatus comprising an electric igniter for said pilot burner energized by operation of said controlling means, a normally closed solenoid valve in series circuit with said igniter and intercepting the fuel supply to the pilot burner, a control relay having a timing element connected in parallel circuit with said solenoid valve and operable to delay actuation thereof to open position until the igniter reaches igniting temperature, a normally closed solenoid valve electrically connected with said igniter and pilot burner solenoid valve for preventing the supply of fuel from passing to the main burner from said controlling means, means operable by said pilot burner for governing the operation of said main burner solenoid valve to open position, and means responsive to actuation of the pilot burner solenoid valve for opening and closing the circuit of said main burner solenoid valve.

7. A safety control apparatus for gaseous fuel burners having main and pilot burners and means for controlling the supply of fuel thereto,

said apparatus comprising an electric igniter for said pilot burner energized by operation of said controlling means, a normally closed solenoid valve in series circuit with said igniter and intercepting the fuel supply to the pilot burner, a control relay having a timing element connected in parallel circuit with said solenoid valve and operable to delay actuation thereof to open position until the igniter reaches igniting temperature, a normally closed main burner solenoid valve connected in parallel circuit with said igniter and pilot burner solenoid valve for preventing the supply of fuel from passing to the main burner from said controlling means, a thermal resistance element connected in parallel circuit with said main burner solenoid valve and exposed to a flame upon operation of the pilot burner for governing the operation of said last named valve, and a switch connected in series circuit with said main burner solenoid valve and responsive to actuation of the pilot burner solenoid valve for opening and closing the circuit of said main burner solenoid valve.

8. A safety control apparatus for fuel burners having a main burner, a pilot burner, means for supplying fuel to said burners, an electric igniter for said pilot burner, separate electrically operable means energizable for actuation from closed to open position for admitting the supply of fuel to the main and pilot burners, an energizing circuit for said igniter and fuel admitting means, a control relay having a timing element in shunt with the pilot burner fuel admitting means, said shunt being established upon energization of said circuit and removable by operation of said relay after a time-delay period dur-.

ing which said fuel admitting means remain closed and said igniter reaches igniting temperature,'and a thermal resistance element adapted to be exposed to the flame of said pilot burner and having normally a relatively low resistance and a positive temperature coeflicient of resistance connected in shunt with said main burner fuel admitting means, said last named shunt being adapted to prevent actuation of said main burner fuel admitting means until said element is heated by the flame of the pilot burner.

9. A control system for fuel burners having main and pilot burners and means for supplying fuel thereto comprising in combination, a source of electrical energy, electrically operated means connected to said source for controlling the w supply of fuel to the main burner, said controlling means having an initial closed position preventing fuel supply to the main burner and being actuable to an open position when current of sufficient value is supplied to said controlling means, a thermal resistance element shunting said controlling means and being located to be heated by a flame at the pilot burner, said resistance element having insufiicient-resistance value until heated by said flame for current of said suiiicient value to be supplied to said controlling means, and switching means having a timing element for short-circuiting said controlling means for-the period during which said resistance element is becoming heated, whereby current of said suiiicient value for causing actu ation of said controlling means is supplied thereto upon operation of said switching means to discontinue the said short circuit.

SAMUEL G. ESKEN. CHARLES K. STRDBEL. 

